Devices for amplifying force comprising a horizontal frame which is fixed to a wall of a building and which carries an arm extending in a vertical direction are already familiar. The lower extremity of the arm includes an interface for receiving a tool such as a drill, a screw-driver or a riveter. The user operates the device by actuating a control unit provided with a vertical force sensor. When the device for amplifying force detects a vertical control force on the sensor, it then controls an actuator (generally a jack) in such a way as to apply a vertical force to the tool that is proportional to the force applied to the control unit.
Also familiar from document WO2012/149402 is a device for amplifying a lifting force comprising a tracked platform supporting a lifting arm operated by a user. A suchlike device permits the easy amplification of a vertical force, but it is ill-adapted to the amplification of forces comprising a majority horizontal component.
The implementation of civil engineering works such as rafts, roads or even building slabs frequently requires a product (concrete, bitumen, etc.) to be “drawn” with the aid of a rake with the aim of leveling its surface. Such-like movements place demands on the back and the arms of the operators and are a source of numerous traumas and industrial accidents. The variable direction of the force (the inclination of the rake in relation to the ground changes as its movement progresses) does not allow the adaptation of the amplifiers of mono axial forces that are familiar to a suchlike application.
No device exists, therefore, which allows the force to be applied to a rake to be supplemented, at least partially, and which allows rapid movement of the user as the task of raking proceeds. Finally, the entirety of the known force amplifiers contain delicate mechanisms (control unit, actuators) which are not adapted to the particularly challenging conditions encountered when working on a construction site.